Over a quarter million (>250,000) infants continue to become infected with HIV-1 annually, despite widespread availability of maternal-infant antiretroviral (ARV) prophylaxis. Approximately half of these infant HIV-1 infections occur via breastfeeding, a mainstay of infant growth and survival in developing regions. Therefore, designing safe strategies to further reduce breast milk HIV-1 transmission is crucial to ending the global pediatric HIV-1 epidemic. The oral cavity is a unique environment for establishment of HIV-1 infection and the associated pyroptotic cell death of CD4+ T cells in lymphoid tissues, such as the tonsils. Blocking the establishment of the oral HIV-1 reservoir and subsequent systemic spread in infants is key to interrupting HIV-1 acquisition and limiting the size of the initial virus reservoir, which may be required to achieve infant HIV-1 remission or cure. Remarkably, despite chronic, daily mucosal virus exposure for up to two years of life, the majority (~90%) of HIV-1-exposed breastfeeding In fact, several breast milk factors with innate HIV-1 inhibitory activity have been identified, including our recently discovery of the HIV-1-neutralizing protein Tenascin-C (TNC). infants are protected against HIV-1 acquisition, suggesting that there are protective factors in breast milk that may block establishment of the HIV-1 reservoir. However, there is a gap in our understanding of how these innate HIV-1 inhibitors in breast milk impact establishment of the oral HIV-1 reservoir and the pyroptotic spread of HIV-1 in oral lymphoid tissues. We hypothesize that innate anti-viral and anti-inflammatory factors in breast milk work in concert to block establishment of the HIV-1 reservoir and reduce the subsequent pryoptotic cell death of CD4+ T cells in oral lymphoid tissues. In this proposal, we aim to define the impact of innate factors in breast milk on the establishment of the oral HIV-1 reservoir, HIV-1-induced pyroptotic cell death, and systemic viral spread from oral lymphoid tissues. Moreover, we will attempt to harness the innate anti-HIV-1 properties of breast milk by producing a more potent, multimeric derivative of TNC's active domain and investigate its ability to limit the oral HIV-1 reservoir and the virus-induced pyroptotic cell deah. Defining the basis of the natural protection provided by breast milk against establishment of the oral HIV-1 reservoir in the majority of HIV- exposed infants is crucial to the development of safe, nontoxic strategies to improve HIV-1-free survival for breastfeeding infants globally.